Pick-up apparatus for magnetic films



Oct. 11, 1932 T. H. NAKKEN 1,882,336

PICK-UP APPARATUS FOR MAGNETIC FILMS Filgd May 21, 1929 PIE. 1.

(UDDUCIDDDUDDDDDDD IN'VENTOR THEODORUE H. NHKIKEIN FIG. q. fiBY M ATTORN Y Patented Oct. 11, 1932 UNITED STATES- PATENT OFFICE THEODOBUS' H. NAKKEN, OF BROOKLYN, NEW YORK, ASBIGNOB TO NAKKEN PATENTS CORPORATION, A CORPORATION OF DELAWARE I PICK-TIP APPARATUS FOR MAGNETIC FILES Application filed May 21, 1929. Serial No. 884,874.

This invention relates to the transformation of a sound record into reproduced sound through the medium of magnetism and electricity. More particularly, an object of the c invention is to produce improved apparatus for picking up a sound record in the form of varying transverse amounts of magnetic material on or in the form of a thin strip of material like a film band or ribbon.

'.-'.O A further object of the invention is to improve both the recording of sound in magnetic material and the transforming of a so recorded sound record into sound.

In carrying out the general object of the invention an important feature is to provide for the picking up of sound from a record in magnetic material with a minimizing of distortion and with a minimizing of the levelling off of the actual record of sound waves. In other words, an important feature is the provision of means for picking up of such a sound record with faithfulness and the transforming of the same faithfully into reproduced sound or another record of the initial sound record.

The above and further objects of the invention will be understood from the illustrative embodiment of my invention described in the following specification in connection with the accompanying drawing sole- 1y for purposes of illustration and not limitation.

In the drawing, Fig. 1 is an enlarged face view of a band in the form of a film embodying two sound records in magnetic material which are suitable for the practice of my invention; Fig. 2 is a similar view showing a film embodying one such sound record accompanied by four frames of a motion picture; Fig. 3 is a perspective view of a part of my pick-up apparatus; and Fig. 4 is a diagrammatic view illustrating the assemblage of one form of my complete apparatus.

In the present application I will describe only some of the forms which my sound record in magnetic material may embody, it being understood that the method of producing them may be any method known to the art or any of those methods described in my copending application filed on even date herewith and now known as Days docket 2665A, Ser. No. 364,875.

A strip, ribbon or band of sheet material A is shown in Fig. 1 in the form of a motion picture film provided with the usual sprocket perforations 1 and 2 along opposite edges of the film. This film is provided with two sound records, one adjacent to the perforations 1 and localized between the lines 3 and 4, and another adjacent to the perforations 2 and localized between the lines 5 and 6'. The sound record is in the form of teeth or transverse lines 7 in one instance and 8 in the other. The teeth 7 extend laterally inwardly from a continuity band 9 which like the teeth 7 comprise or are composed of magnetic material. Along the opposite edge of the film the continuity band 10 extends to the extreme edge of the film and surrounds the perforations 2. In both cases the teeth 7 and 8 alternate with similar spaces 11 and 12 which demark the absence of magnetic material or a lesser amount of magnetic material in the direction of the thickness of the film.

As pointed out in my copending application, the continuity band connecting with each of the teeth 7 or 8 is of prime importance as the record in magnetic material is con strained to be made by electrolytic deposition. In such case the continuity band serves as a conductor directly to the root of each toothv which with the band may first be in the form of a silver deposit or a deposit of any conducting material not necessarily magnetic so that the continuity band with the aid of a suitable electrolyte effects an iron deposit or a deposit of any suitable magnetic material without any difiiculties due to varying conductivity.

It is important also to localize the conductivity bands along the locality of the perforations 1 and 2 and to utilize for the sound record the space relatively inward from the continuity bands. In this way great economy is effected particularly when the continuity band embraces the perforations as shown for the band 10 in Fig. 1.

In Fig. 2 the combination of one of my magnetic sound records with the usual frames for moving pictures is shown which brings out the economy of positioning of the continuity band 9, sound record 7 and frames 13.

In Fig. 3 I have diagrammatically illustrated in perspective a preferred form of part of my pick-up apparatus.

B is a core preferably in the form of a permanent magnet carrying the pick-up coil 20, the terminals 21 and 22 of which may energize any translating device such as the primary 23 of transformer C. The poles 24 and 25 of the permanent magnet B are terminated in two parallel opposedknife edges 26 and 27 adapted to straddle one of the sound records 7 or 8 as indicated in Fig. 3.

The positioning should be such that these knife edges do not touch either surface of the band A and therefore have no destroying or abrasive action thereon but otherwise their positioning should be such as to reduce the air up there between to a minimum. It is pre erred that the knife edges be limited in extent to the transverse length of the sound record and that the transverse direction of these knife edges relatively to the band A correspond substantially to the direction of the teeth or lines of the sound record itself.

The preferred embodiment is substantially at right angles to the length of the band although it is understood that the spirit of: so the invention would be available for improvement even though the teeth or lines of the sound record and the knife edges of the poles were inclined and only had a substantial component at right angles to the direction of the moving of the film or band.

l It is to be understood, of course, that the usual guiding and feeding mechanism to cause a .traverse of the sound record between the knife edges 26 and 27 is contemplated 4o in the dia am of Fig. 4. Any of those commercially employed in connection with sound on film feeds are contemplated.

It is also contemplated that the core B is not of necessity limited to the construction shown.

In its operation the reluctance of an existing magnetic circuit traversing the circuit between the knife edges 26 and 27 is varied by the traverse of the sound record in the form of the teeth 7 or 8 across the knife edges. Corresponding currents are set up in the coil 20 which in turn correspondingly energize the transformer C, the secondary 30 of which is connected with the input side of a triode amplifier D which through the medium of an interstage transformer E controls a second triode amplifier F which in turn through a third transformer G effects a third am lification by means of the triode 6.0 amplifier the plate clrcuit of which is employed to reproduce sound by means of the oud speaker I. It is, of course, to be understood that any suitable operating circuits and sources of energy may be employed and that I am not limited to the precise showing of such devices as embodied in my Fig. 4. In fact, I contemplate the employment of my pick-up device shown in Fi 3 in conjunction with the energizing 0 any amplifier system for any suitable urpose.

What I claim and esire to secure by United States Letters Patent is:

A motion fpicture film having marginal sprocket per orations comprising centrally positioned photographic images for purposes of picture projection but leaving a narrow margin between one row of perforations and said images free from picture projection image; a multiple layer metallic sound record having a sound modulated portion localized within said margin and an integral continuity band extending between and outside of said perforations, all of which sound record consists of an under layer of nonmagnetic conducting material and a superposed deposit of magnetic metal.

- THEODORUS H. NAKKEN. 

